This invention relates to an optical coupling arrangement, and particularly, though not exclusively, to an arrangement for Coupling an optical light source to an optical fiber.
High speed data and telecommunications systems designers are always forced to compromise between system bandwidth and data rate. In comparison to pure electrical circuits, the use of optoelectronic devices can increase data rates with relatively little bandwidth trade-off.
High performance semiconductor laser packages that could enhance system performance were developed more than a decade ago. However, one difficulty found in the assembly of such packages is in achieving and maintaining the precise fixturing and alignment necessary between the optical fiber core (typically .about.9 .mu.m in diameter) and the laser emitting facet (typically having a dimension of .about.2-4 .mu.m) in order to ensure good optical coupling.
Typically, optical fibers are locked in place using a fixative such as UV-cured epoxy or solder. Optical fiber to laser alignment techniques available today can ensure alignment tolerances of less than .+-.0.1 .mu.m. However, the ability to lock and hold this alignment over operating temperature extremes has yet to be proven reliable. Movement of the optical fiber relative to the laser is almost always encountered, due to the intrinsic nature of the different linear coefficients of expansion of the materials used. Coupling losses due to such movements may not be immediately apparent, but have been frequently found to materialize subsequently, causing severe performance degradation.